As a method for preparing a 4-aminotetrahydropyran compound and an acid salt thereof, it has conventionally been disclosed a method in which tetrahydropyran-4-one, ammonium acetate, molecular sieve powder and sodium cyanoborohydride are reacted in ethanol to give a 4-aminotetrahydropyran with yield of 12% (see, for example, Japanese PCT Laid-Open Publication Hei.11-510180 (pages 66 to 67)). However, according to this method, there are problems that a markedly excessive amount of ammonia source (for example, ammonium acetate) must be used, and also, a reaction system is complicated so that operations for the reaction are troublesome and yield of the objective product is low.
Also, with regard to 2-substituted tetrahydropyranyl-4-sulfonate which can be used as a synthetic starting material for the above-mentioned compound and a process for preparing the same have never been known.
An object of the present invention is to provide an industrially suitable process for preparing a 4-aminotetrahydropyran compound and an acid salt thereof which does not require complicated operations and can prepare a 4-aminotetrahydropyran compound and an acid salt thereof with a simple and easy method.
Another object of the present invention is to provide an industrially suitable 2-substituted tetrahydropyranyl-4-sulfonate and a process for preparing the same which can solve the above-mentioned problems, and can prepare the 2-substituted tetrahydropyranyl-4-sulfonate under mild conditions with a simple and easy method and a high yield.